Voltage compensated wire controlled snap action device



April 8, 1964 H. G. SHBERG 3,131,271

VOLTAGE COMPENSATED WIRE CONTROLLED SNAP ACTION DEVICE Filed Jan. 19, 1961 4 Ill 24' w 4 L 4a INVENTOR AQ-MM/NG G. ,Susgwc;

ATTO RN EYS United States Patent O 3,131,271 VOLTAGE COMPENSATED WIRE CONTROLLED SNAP ACTION DEVICE Hernming G. Siiherg, Qranford, N.J., assignor to Tung sol Electric Inc a corporation of Delaware Filed Jan. 19, 1961, Ser. No. 83,721 Claims. (Cl. 200-113) The present invention relates to thermal snap action devices of the type wherein expansion and contraction of a wire or ribbon with passage of current therethrough, control the operation of the device. Various devices of this general type are employed for controlling turn signals of automobiles, as thermal relays and as circuit breakers. In most if not all of the devices of this type changes in supply voltage affect the operation of the switching device. In the case of flashers, the rate of flashing and the ratio between on and 011 periods of lamps controlled thereby will vary when the supply voltage varies. The present invention comprises means for compensating in such thermal responsive devices for change in supply voltage so as to render such devices substantially independent of voltage changes.

The compensation for voltage variations in the devices of the invention is obtained by the provision of an auxiliary expansible wire which is connected across the source of energy in series with a suitable resistance and which is so coupled to the means for introducing tension in the operating expansible wire of the device as to increase the tension therein when the voltage increases and decrease the tension therein when the voltage decreases. By securing an end of the pull wire to a spring arm which is biased in a direction to increase the tension in the pull wire and then by controlling the position of such spring arm by the auxiliary pull wire, automatic compensation of tension in'the operating pull wire is obtained when the supply voltage varies. Thus when the voltage increases the auxiliary pull wire expands under the increased current therethrough. Expansion of the auxiliary pull wire permits the spring arm to which it is fixed to move in a direction to increase the tension in the operating pull wire thus counteracting the effect of the higher voltage on the operating pull wire. Conversely, when the voltage of the source decreases the consequent contraction of the auxiliary pull wire operating through the spring arm reduces the tension in the operating pull wire and again thereby compensates for decreased voltage of the source.

For a better understanding of the invention and of a specific embodiment thereof reference may be had to the accompanying drawing of which:

FIG. 1 is a side view of a snap action device provided with the voltage compensating means of the invention;

FIG. 2 is a plan view of the device of FIG. 1; and

FIG. 3 is a perspective view of the snap blade of the device of FIGS. 1 and 2.

In the drawing the new voltage compensating means of the present invention is shown as incorporated in a flasher of the general type disclosed and claimed in applicant's copending application Serial No. 65,789, filed October 28, 1960, now Patent No. 3,052,780. The flasher elements are mounted on a base 2 of insulating material through which extend terminal members 4, 6 and 8. Terminal 4 has secured thereto an angle piece 10 upon which is mounted an electric contact 12. Terminal 6 above the base portion terminates in a yoke member 14 on spaced arms of which is mounted one end of a snap plate 16, and terminal 8 above the base plate terminates in a bracket 18 having an upstanding flange 20 which supports a V- shaped element 22. A spring arm 24 is secured to the upper horizontally extending portion of terminal 4 so as to have good electrical contact therewith. It is the position of the upwardly extending portions of spring 24 "ice which controls the tension, when cold, of the operating pull wire 26 of the flasher. One end of the pull wire 26 is insulatedly anchored as by a bead 28 in the spring arm 24 and the other end of the pull wire is fastened to one arm of an L-shaped lug 30, the other arm of which engages the snap plate 16. Lug 30 is mounted on one end of a leaf spring 32, the other end of which is secured to the yoke member 14. Beyond the head 28 the pull wire is coiled to form a resistance 34 the other end of which is connected to the yoke 14. Also anchored in the spring arm 24 is one end of an auxiliary wire 36 the other end of which is insulatedly mounted as by a bead 38 in one leg of the V-shaped member 22. Beyond the head 38 the auxiliary wire is coiled to form a resistance 40, the other end of which is welded to the member 22. The particular snap plate of this embodiment of the invention is shown in perspective in FIG. 3. It comprises a rectangular sheet of resilient material that is transversely creased at 44 and then bowed about a longitudinal axis between the creases 44 and the adjacent mounted end of the blade, the bowing being introduced by means of a screw 46 which threads into the base 2 and urges the arms of the yoke member 14 toward each other thereby curving the blade between the points of attachments to the arms of the yoke member. Screw 46 also serves to secure the leaf spring 32 to the frame. Lug 30 has a turned down end which engages the snap blade in the neighborhood of the creases 44. When the tip of the lug 3%) increases the pressure on the blade the free end of the blade moves upwardly and conversely, when the pressure on the blade exerted by the tip of the lug decreases the free end of the blade moves downwardly under the stresses introduced by the transverse creases 44 therein and by the longitudinal curvature resulting from the manner of mounting the blade on the yoke member. On one side of the free end of the blade is a contact 48 which in the initial cold position of the parts shown in FIG. 1 engages contact 12 under pressure. A screw 50 extending through the two arms of the V-shaped member 22 serves to adjust the initial tension in the auxiliary wire 36.

The operation of the above described device is as follows: The tension in auxiliary pull wire 36 is first adjusted by means of the screw 50 until contacts 48 and 12 are brought into engagement. It then a lamp load is connected to terminal 6, ground to terminal 8 and a source of energy as for example, a battery having a grounded negative terminal, is connected to terminal 4 current will flow from terminal 4 through the closed contacts 12 and 48, the blade 16 to terminal 6 and the lamp load. Current will also flow from terminal 4 to the spring arm 24, auxiliary wire 36, resistance 40 to terminal 8 and ground. This current through the auxiliary wire will cause expansion of that wire with consequent partial release of the spring arm 24. Accordingly spring arm 24 will move in a direction to increase the tension on the operating pull wire 26. Increase in tension in the pull Wire 26 causes the free end of the blade 16 to snap away from contact closing position. Thereupon the lamp circuit is opened at the contacts but closed through resistor 34 and pull wire 26. This additional resistance in the lamp circuit will be insufiicient to cause the lamps to light but suflicient to cause expansion of the pull wire 26. Upon expansion of pull wire 26 the pressure exerted by lug 30 on the snap plate reduces sufficiently to permit the snap plate to return to contact closing position. Thus the device will continue to operate as a flasher with expansion and contraction of the pull wire 26. It now there is a change in voltage this change will be reflected in a change in current in the auxiliary wire 36 and consequently a change in the position of spring arm 24. For example, an increase in operating voltage will expand the auxiliary wire 34 and result in an increase in tension in pull wire 26, such increase in tension being just suflicient to compensate for the reduction in tension in the pull wire 26 occasioned by the increase in voltage. Conversely, when the voltage decreases the reduction in length of auxiliary wire 34 will move the spring arm 24 in a direction to decrease the tension in pull wire 26 and therefore compensate for the reduction in its length occasioned by the reduction in the supply voltage.

The invention has now been described as incorporated in one particular flasher construction, that of the said copending application. Obviously the novel voltage compensating means of the invention could be employed in other hot wire controlled devices, whether flashers, or relays or circuit breakers. For example, the compensating means of the invention could be readily incorporated in the wire controlled switch of US. Patent No. 2,761,931, dated September 4, 1956, of Joseph Schmidinger, or in the thermal switch and relay of US. Patent No. 2,388,712 of the same patentee, or in electromagnetic flasher of Schmidinger Patent No. 2,715,187 or in the thermo responsive switch of Schmidinger Patent No. 2,906,835.

The following is claimed:

1. In a snap action maintaining constant rate of flashing by device wherein expansion and contraction of a tensioned pull means with change in current therethrough control the operation of the device, means for compensating for voltage variations of the supply, comprising an auxiliary expansible wire, spaced arms anchoring said auxiliary wire at spaced locations, at least one of said arms being spring biased to tension said auxiliary wire, said spring biased arm serving also to tension the operating pull means of the device, and circuit means electrically independent of said operating pull means for connecting said auxiliary wire in circuit with the supply whereby when the supply voltage increases said auxiliary wire expands reducing the tensile force exerted against the spring bias of said arm and thereby increasing the tensile force exerted on the operating pull means by said arm.

2. In a snap action device according to claim 1, means associated with the other of said arms for adjusting the tension of said auxiliary wire.

3. A snap action device comprising an element movable between two circuit controlling positions, means for biasing said element toward one of said positions, an expansible pull means connected under tension to said element and when cold holding said element in the other of said positions, spring means connected to said pull means to tension the same, means for compensating for change in supply voltage comprising an auxiliary pull means fixed at one location and connected under tension to said spring means to decrease the tension introduced into said first mentioned pull means when the auxiliary pull means contracts as a result of decrease of supply Voltage and to increase the tension in the first mentioned pull means when the auxiliary pull means expands as a result of increase in supply voltage, circuit connections to said auxiliary pull means independent of the position of said element to maintain the current through said auxiliary pull Wire dependent only on the supply voltage, and circuit connections to said first mentioned pull means and to said element, said element when in the position toward which it is biased shunting said first mentioned pull means and thereby permitting it to cool, whereby said device operates as a circuit interrupter.

4. The snap action device according to claim 3 including means at said fixed location for adjusting the tension in said auxiliary pull means.

5. The snap action device according to claim 3 wherein said circuit connections to said first mentioned pull means and said circuit connections to said auxiliary pull means each include a resistor, the resistor in the circuit connections to said first mentioned pull means being shunted together with said first mentioned pull means when said element is in the position toward which it is biased.

References Cited in the file of this patent UNITED STATES PATENTS 959,827 Wohl et al. May 31, 1910 2,388,712 Schmidinger Nov. 13, 1945 2,641,666 Sitzer June 9, 1953 2,689,283 Pulvari Sept. 14, 1954 2,890,645 Bergsma June 19, 1959 FOREIGN PATENTS 29,930 Norway Dec. 27, 1921 1,115,160 France Dec. 26, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3, 181,271 April 28 1964 Hemming Go Siiherg It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, lines 23 and 24, strike out "maintaining constant rate of flashing 'by", and insert the same after "means for" in line26, same column 3.

Signed and sealed this 15th day of September 1964.

(SEAL) Attest:

ERNEST w. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,131,271 April 28, 1964 Hemming G Siiberg It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

lines 23 and 24, strike out "maintaining Column 3,

and insert the same after "means constant rate of flashing by", for", in line 26 same column 3.

Signed and sealed this 15th day of September 1964.

(SEAL) Attest:

EDWARD J. BRENNER ERNEST W. SWIDER Attesting Officer Commissioner of Patents 

1. IN A SNAP ACTION MAINTAINING CONSTANT RATE OF FLASHING BY DEVICE WHEREIN EXPANSION AND CONTRACTION OF A TENSIONED PULL MEANS WITH CHANGE IN CURRENT THERETHROUGH CONTROL THE OPERATION OF THE DEVICE, MEANS FOR COMPENSATING FOR VOLTAGE VARIATIONS OF THE SUPPLY, COMPRISING AN AUXILIARY EXPANSIBLE WIRE, SPACED ARMS ANCHORING SAID AUXILIARY WIRE AT SPACED LOCATIONS, AT LEAST ONE OF SAID ARMS BEING SPRING BIASED TO TENSION SAID AUXILIARY WIRE, SAID SPRING BIASED ARM SERVING ALSO TO TENSION THE OPERATING PULL MEANS OF THE DEVICE, AND CIRCUIT MEANS ELECTRICALLY INDEPENDENT OF SAID OPERATING PULL MEANS FOR CONNECTING SAID AUXILIARY WIRE IN CIRCUIT WITH THE SUPPLY WHEREBY WHEN THE SUPPLY VOLTAGE INCREASES SAID AUXILIARY WIRE EXPANDS REDUCING THE TENSILE FORCE EXERTED AGAINST THE SPRING BIAS OF SAID ARM AND THEREBY INCREASING THE TENSILE FORCE EXERTED ON THE OPERATING PULL MEANS BY SAID ARM. 